The Minister for Foreign Affairs has warned of the "devastating humanitarian consequences" of nuclear weapons following a threat by Russian President Vladimir Putin.
Simon Coveney said the alert "considerably heightens the risk of catastrophic miscalculation".
Putin put Russian nuclear deterrent forces on high alert amid tensions with the West over Ukraine on Sunday.
He told state TV that NATO powers have made "aggressive statements" along with the West imposing hard-hitting financial sanctions against Russia, including the president himself.
Putin ordered the Russian defence minister and the chief of the military's General Staff to put the nuclear deterrent forces in a "special regime of combat duty".
His actions have been slammed as dangerous, with the US Ambassador to the UN saying Putin's order shows the Russian leader is "escalating conflict in a manner that is unacceptable".
In a statement on Monday, Minister Coveney also rebuked the move and called for Russia to revoke the order.
“I strongly condemn the announcement by President Putin that he has put Russia’s ‘deterrent forces on special combat duty’," he said.
“This threat of nuclear weapons is utterly unacceptable. President Putin’s announcement represents a dangerous and irresponsible escalation in tensions, and considerably heightens the risk of catastrophic miscalculation.
"There can be no justification for threatening use of nuclear weapons. Ireland has long argued that nuclear weapons offer no security, and their use would result in devastating humanitarian consequences.
"I recall the statement of the heads of the five Nuclear Weapon States, including President Putin, just last month, that ‘a nuclear war cannot be won and must never be fought’."
He added: “I call for Russia to immediately revoke the order to place nuclear weapons on high-alert status, and I urge maximum restraint, de-escalation and the avoidance of any nuclear rhetoric which will only worsen an already dangerous and unpredictable situation.”
